Field and laboratory evaluation of some entomopathogenic fungi against the pink bollworm Pectinophora gossypiella(Saund.) and their side effects on the predatory activity of Orius sp. (Hemiptera: Anthocoridae).

Abstract

Pectinophora gossypiellacauses serious damage to the cotton plant in both quantity and quality during the different stages of their growth. Entomopathogenic fungireceived great attention as a hope for the future of insect control. Orius albidipennis is very common throughout much of the country in cultivated areas, especially in corn and cotton fields. It is usually found in flowers of plants infested with lepidopteran eggs. The efficiency of the used entomopathogenic fungi, Metarhizium anisopliae, Beauveria bassiana and Trichoderma harzianum was evaluated against the newly hatched larvae of Pectinophora gossypiella. The mortality percentages of the newly hatched larvae of P. gossypiella treated with the different concentrations of B. bassiana,M. anisopliaeand T. harzianumincreased gradually with increasing the time elapsed after treatment. Five concentrations of each entomopathogenic fungus under test were prepared to calculate thelethal concentration values (LC50). The tested fungiproved to be effective on larvae of P. gossypiella as depicted by the calculated LC values. The LC50 values in case of the newly hatched larvae were 1.42, 0.98g\l and 3.8x108spores\ml for B. bassiana,M. anisopliaeand T. harzianum,respectively. Application of LC50s of B. bassiana,M. anisopliaeand T. harzianumagainst P. gossypiellapretreated as newly hatched larvae resulted in a mean larval duration of14.04, 15.07 and 13.80 days, respectively, compared to 12.63days forthe control. The mean pupal duration in case ofnewly hatched larvae of P. gossypilla treated with B. bassiana,M. anisopliaeand T. harzianum, was 9.22, 9.36 and 9.40days,respectively, for the LC50values compared to the control (7.32 days). The percentage of newly hatched larvae of P. gossypilla which succeeded in reaching pupation was 48.33, 50 and 50% for LC50 values of B. bassiana,M. anisopliaeand T. harzianum,respectively, compared to 93.33% in case of control. There was a decrease in the percentage of pupae, which succeeded in surviving and giving adults. The